The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
The invention is related in general to equipment and methods for preparing curved fibers.
The inclusion of fibers in fluids for servicing subterranean wells has become a well-known practice. For example, fibers are added to drilling fluids to help minimize lost circulation. Similarly, fibers may be added to cement slurries to help minimize lost circulation; fibers can also improve flexural strength of set cement. In hydraulic fracturing operations, fibers may be added to proppant to help prevent proppant flowback as the well produces. Fibers are also used to improve the solids-carrying capacity of fluids as they are pumped downhole for various purposes.
A thorough presentation of the use of fibers in well-service fluids may be found in the following publications.    Armstrong K. et al.: “Advanced Fracturing Fluids Improve Well Economics,” Oilfield Review 7, no. 3 (Autumn 1995): 34-51.    Abbas R. et al.: “A Safety Net for Controlling Lost Circulation,” Oilfield Review 15, no. 4 (Winter 2003/2004): 20-27.    Bivins C. et al.: “New Fibers for Hydraulic Fracturing,” Oilfield Review 17, no. 2 (Summer 2005): 34-43.    Daccord G. et al.: “Cement-Formation Interactions,” in Nelson E. B. and Guillot D. (eds.): Well Cementing-2nd Edition, Houston: Schlumberger (2006): 191-232.
More recently, it has been discovered that fluids containing fibers (also known as fiber laden fluids) may be used as plugs that prevent the commingling of two other well-service fluids in a tubular body. For example, a fiber-laden fluid may be used to prevent contact between drilling fluid and a cement slurry—fluids that are often incompatible and would cause operational problems should they commingle.
Until now, fibers employed in well-service fluids have been linear; that is, the length of the fiber extends along a straight or nearly straight line. However, it has been discovered that curved fibers have utility in the domain of well-service fluids. This type of fibers is also documented in copending patent application no EP09290761.7 to Services Petroliers Schlumberger.
In civil engineering, so-called “curved fibers”, available, for example, from CNBM International Corporation, 5/F, Longbo Building, 3 Nanlishi Rd., Xicheng District, Beijing City, China, under the product name “Curved Polymer Fibre” are used for the reinforcement of concrete. However, such curved fibers are crimped or twisted in a helical pattern along their length. The bulk fiber shape is still linear, because the helix extends in a straight line.
It therefore remains desirable to have equipment and methods by which curved fibers may be prepared.